1. Field of the Invention
This invention relates to a data recording method and apparatus for recording digital data on a recording medium, such as a magnetic disc, and to a data reproducing method and apparatus for reproducing digital data from the recording medium.
2. Description of Prior Art
Recently, a hard disc drive, in which a magnetic disc, comprised of a metal substrate of e.g., aluminum, having its surface ground smooth, is used as a recording medium, and in which a floating slider, carrying a magnetic head, is floated over a data recording area of the magnetic disc to write or reproduce data, is in widespread use.
The hard disc drive has an extremely high data recording density and is able to store a large quantity of data. Moreover, data recorded thereon can be accessed at an extremely high speed. For this reason, the hard disc drive is widely used as a storage device for storing data processed by a computer.
FIG. 1 shows an illustrative structure of a signal processing circuit in the hard disc drive.
When digital data processed by a data processing device, such as a host computer, referred to below as recording data, is to be recorded on a magnetic disc by a hard disc drive 100, shown in FIG. 1, a recording command first is routed from a data processing device, such as a host computer, to a central processing unit (CPU) 101, whilst the recording data is routed to a host interface 103 in a hard disc controller 102. The recording data, routed to the host interface 103, is temporarily stored in a buffer memory 105, under control by a bus controller 104.
The CPU 101 instructs to a sequencer 106 in which sector on the magnetic disc the recording data is to be recorded, under a recording command routed from the data processing device, such as a host computer.
The magnetic head is positioned on the magnetic disc by a servo control circuit 107 computing the current magnetic head position, based on the position information detected by the magnetic head, and by the driving current of a voice coil motor (VCM) being controlled responsive to the current position of the magnetic head.
If the sequencer 106 has verified that the magnetic head is at the targeted position, it reads out recording data from the buffer memory 105 to route the recording data to an error correcting circuit (ECC) 108. The recording data, routed to the ECC circuit 108, is added to with an error correction code, and is subsequently transferred through a disc interface 109 to a channel IC 110. The channel IC 110 channel-encodes the recording data, transferred thereto over a disc interface 109, to convert the data to binary-valued signals. These signals are written by the magnetic head as magnetization inversion pattern. The operating timing of the disc interface 109 is controlled by the sequencer 106.
If, when the recording data is recorded on the magnetic disc, the servo control circuit 107 detects that, due to an excessively large position signal from the magnetic head, it is difficult to continue the regular operation, the sequencer 106 transfers to a retry mode to perform the operation of re-recording the same sector. The information indicating the difficulty in continuing the regular operation may be routed from the servo control circuit 107 directly to the sequencer 106 or may be routed through the CPU 101 to the sequencer 106.
For reproducing data recorded on the magnetic disc by the hard disc drive 100, a playback command first is routed from a data processing device, such as a host computer, to the CPU 101. The magnetic head then reads out the magnetization inversion pattern from the magnetic disc.
The magnetic head is positioned on the magnetic disc, by the servo control circuit 107 computing the current position of the magnetic head, based on the position information detected by the magnetic head, and by the VCM driving current being controlled responsive to the current position of the magnetic head.
The magnetization inversion pattern, read out for the magnetic disc by the magnetic head, is restored to digital data, referred to below as playback data, by the channel IC 110 performing the operations of waveform equalization, signal detection or channel code decoding. Although the playback data may be corrupted with errors, it is directly transferred to the disc interface 109 in-the hard disc controller 102.
The operational timing of the disc interface 109 is controlled by the sequencer 106. If the sequencer 106 has confirmed that the magnetic head is at a target position, the sequencer retrieves playback data from the channel IC 110, over the disc interface 109, to route the playback data to the ECC communication 108.
The ECC circuit 108 decodes the error correction code appended to the playback data to execute error correction and detection. If an 8-symbol error correction code is appended to the playback data, the ECC circuit 108 is able to correct the error of the playback data up to the fourth symbol. However, if the number of symbols to be corrected is larger, the error correction is time-consuming thus lowering the processing speed. Therefore, in the above case, error correction up to the second symbol is made without exploiting the correction capability of the ECC circuit 108 to a maximum extent. If an error is found to be present in the as-corrected playback data, the sequencer 106 transfers to a retry mode to re-reproduce the same sector. In this case, the correction capability of the ECC circuit 108 is exploited to its maximum extent to correct the playback data for errors.
The hard disc drive is configured to execute decoding usually at a high speed and to raise the retry and correction capability only at the time of error occurrence to expedite the overall processing speed such as to maintain data reliability.
The playback data, processed by the ECC circuit 108 with error correction and detection, is temporarily stored in the buffer memory 105, under control by the bus controller 104. The playback data, stored in the buffer memory 105, is sequentially transferred over the host interface 103 to a data processing device, such as a host computer.
Meanwhile, in keeping pace with the recent progress in the digital technique, digitized moving picture data is routinely processed on a computer. For providing means for storing moving picture data, thus processed on the computer, a demand has been raised for using a hard disc drive.
For recording and/or reproducing the moving picture data, a data stream making up the moving picture is desirably recorded and/or reproduced in real-time. Therefore, if the moving picture data is to be reproduced using the above-described hard disc drive 100, it is necessary to sequentially transfer the playback data transiently stored in the buffer memory 105 from the buffer memory 105 to the data processing device, such as a host computer. The result is that, if an error is found to persist in the as-corrected playback data, and the retry operation is repeatedly performed until the error ceases to be detected, it may be an occurrence that the buffer memory 105 becomes void to stop the reproducing operation.
If, in order to evade this inconvenience, moving picture data is to be reproduced, using the hard disc drive 100, the processing of directly transferring the playback data corrupted with errors to the data processing device, such as a host computer, is occasionally performed without performing the retry operation suffering from temporal indefinite elements. However, in such case, the reproduced moving picture data is deteriorated inevitably in picture quality.
On the other hand, if the moving picture data is recorded using the aforementioned hard disc drive 100, recording data is sequentially transferred from the data processing device, such as a host computer, to the hard disc drive 100, for storage in the buffer memory 105. Thus, if a writing error is produced, but the retry operation is repeatedly performed until a writing error ceases to be produced, there is a risk that the buffer memory 105 undergoes overflowing to halt the recording operation.
In order to evade such inconvenience in recording moving picture data with the hard disc drive 100, data corrupted with a writing error may sometimes be directly discarded without performing the retry operation suffering from temporal indefinite elements. However, in such case, the lacking moving picture data is not reproduced, so that, if pre-set moving picture data is reproduced, the reproduced moving picture data is necessarily deteriorated in picture quality.
It is therefore an object of the present invention to provide a data recording method and apparatus in which moving picture data, required to be handled in real-time, may be recorded so that data with as high data quality as possible will be reproduced on reproduction, as the real-time performance is maintained, by efficiently utilizing data storage means, such as buffer memories.
It is an object of the present invention to provide a data reproducing method and apparatus in which moving picture data, in particular moving picture data, required to be real-time data, can be reproduced as data with as high data quality as possible, as the real-time performance is maintained.
In one aspect, the present invention provides a data recording apparatus for recording compressed moving picture data on a recording medium, including data storage means for transiently storing moving picture data to be written in the recording medium, retry means for re-writing data corrupted with a writing error on the recording medium if such writing error has been produced during the recording operation, and switching means for switching the operation of the retry means depending on the state of the data storage means at the time of production of the writing error.
In this data recording apparatus, the moving picture data written on the recording medium are sequentially stored for the time being in data storage means, herein buffer storage means. It is noted that picture data making up the moving picture data, read out from the data storage means, is sequentially recorded on the recording medium.
If, in sequentially recording the moving picture data, read out from the data storage means, a writing error is produced, switching means switches between performing and not performing the retry operation of re-writing data corrupted with the writing error on the recording medium depending on the state of writing error occurrence of the data storage means.
In more detail, if the free space of the data storage means on writing error occurrence exceeds a data volume stored in the data storage means during the time moving picture data of the data volume written at a time in the data storage means is written on the recording medium, the retry means is operated to re-write the data corrupted with the writing error on the recording medium. If conversely the free space of the data storage means on writing error occurrence is lesser than a data volume stored in the data storage means during the time moving the picture data of the data volume written at a time in the data storage means is written on the recording medium, the retry means is not operated.
In the present data recording apparatus, the switching means switches between operating and not operating the data storage means depending on the state of the data storage means at the time of occurrence of the writing error. For example, if there is sufficient free space in the data storage means at the time of occurrence of the writing error, the retry means is operated to improve the data quality, whereas, if there is no sufficient free space in the data storage means at the time of occurrence of the writing error, the retry means is not operated to assure the real-time performance. Thus, it is possible to record moving picture data, required to be real-time data, so that data of the highest possible data quality will be reproduced as real-time data.
In another aspect, the present invention provides a data recording apparatus for recording digital data on a recording medium including discriminating means for discriminating whether the digital data is compressed moving picture data or other data, data storage means for transiently storing the digital data written on the recording medium, retry means for rewriting data corrupted with a writing error produced during the recording operation on the recording medium and switching means for switching between operating and not operating the retry means, responsive to the state of the data storage means at the time of occurrence of the writing error, if the discriminating means verifies the digital data to be the compressed moving picture data.
In this data recording apparatus, the digital data written on the recording medium is transiently stored in the data storage means. The digital data read out from the data storage means is sequentially recorded on the recording medium. It is up to the discriminating means to verify whether the digital data recorded on the recording medium is compressed moving picture data or other data.
If, in this data recording apparatus, the digital data to be recorded is verified by the discriminating means to be compressed moving picture data, the switching means switches between operating and not-operating the retry means performing the rewriting of the data corrupted with the writing error on the recording medium, depending on the state of the data storage means prevailing at the time of occurrence of a writing error, in case the writing error has occurred during recording of the digital data read out from the data storage means sequentially on the recording medium.
In the present data recording method, in which, in recording the compressed moving picture data on the recording medium, switching between performing and not performing the retry operation is made depending on the state of the data storage means prevailing at the time of generation of the writing error. Thus, in recording moving picture data, required to be real-time data, the picture can be recorded so that moving picture data with as high a data quality as possible will be reproduced as real-time data.
In still another aspect, the present invention provides a data recording method wherein, in recording compressed data on a recording medium, switching is made between performing and not performing a retry operation of re-writing data corrupted with a writing error produced during the recording operation depending on the state of data storage means transiently storing the moving picture data written on the recording medium at the time of occurrence of the writing error.
In the present data recording method, switching is made between performing and not performing the retry operation of re-writing data corrupted with a writing error on the recording medium depending on the state of the data storage means prevailing at the time of the occurrence of the writing error. In more detail, if the free space of the data storage means at the time of occurrence of the writing error exceeds the amount of data stored in the recording medium during the time picture data of a data volume written at a time on the recording medium is written on the recording medium, the retry operation is performed, whereas, if the free space of the data storage means at the time of occurrence of the writing error is lesser than the amount of data stored in the recording medium during the time picture data of a data volume written at a time on the recording medium is written on the recording medium, the retry operation is performed.
In the present data recording method, switching is made between performing and not performing the retry operation depending on the state of the data storage means prevailing at the time of error occurrence of the writing error, so that, if there is sufficient free space in the data storage means at the time of occurrence of the writing error, the retry operation is performed to improve the data quality, whereas, if if there is not sufficient free space in the data storage means at the time of occurrence of the writing error, the retry operation is not performed to assure the real-time performance. Thus, it is possible to record moving picture data, required to be real-time data, so that data with as high a quality as possible will be reproduced as real-time data.
In still another aspect, the present invention provides a data recording method for recording digital data on a recording medium including discriminating whether the digital data is compressed moving picture data or other data, wherein, if the digital data is verified to be compressed moving picture data, switching is made between performing and not performing a retry operation depending on the state at the time of error occurrence of a writing error of data storage means transiently storing the digital data to be written on the recording medium, in case the writing error has occurred during the recording operation, the retry operation being the operation of re-writing data corrupted with the writing error on the recording medium.
If, in this data recording method, the digital data to be recorded is verified to be compressed moving picture data, switching between performing and not performing the retry operation of re-writing data corrupted with the writing error is made depending on the state of the data storage means prevailing at the time of error occurrence of the writing error.
In the present data-recording method, if the digital data to be recorded is verified to be compressed moving picture data, switching between performing and not performing the retry operation depends on the state of the data storage means prevailing at the time of error occurrence of the writing error. Thus, it is possible to record moving picture data, required to be real-time data, so that data with as high a quality as possible will be reproduced as real-time data.
In still another aspect, the present invention provides a data reproducing apparatus for reproducing compressed moving picture data from a recording medium including data storage means for transiently storing moving picture data read out from the recording medium, retry means for re-reading from the recording medium data corrupted with an error produced in the moving picture data read out from the recording medium and switching means for switching the operation of the retry means responsive to the state of the data storage means prevailing at the time of error occurrence of the error in the moving picture data read out from the recording medium.
In this data reproducing apparatus, the moving picture data, read out from the recording medium, is transiently stored in the data storage means. If an error has occurred in the moving picture data read out from the recording medium, the switching means switches between performing and not performing the retry operation of re-reading out error-corrupted data from the recording medium depending on the state of the data storage means prevailing when the error has occurred in the moving picture data read out from the recording medium.
In more detail, the switching means switches the operation of the retry means so that, if the amount of data stored in the data storage means when an error has occurred in the moving picture data read out from the recording medium exceeds the amount of data transferred from the data storage means during the time the moving picture data of a data quantity read out at a time from the recording medium is read out from the recording medium, the retry means is operated to re-read the error-corrupted data from the recording medium, whereas, if the amount of data stored in the data storage means when an error has occurred in the moving picture data read out from the recording medium is lesser than the amount of data transferred from the data storage means during the time the moving picture data of a data quantity read out at a time from the recording medium is read out from the recording medium, the retry means is not operated.
That is, in the present data reproducing apparatus, the switching means switches the operation of the retry means, depending on the state of the data storage means prevailing when the error has occurred in the picture data read out from the recording medium, so that, if a sufficient amount of moving picture data has been stored on the recording medium when an error has occurred in the moving picture data read out from the recording medium, the retry means is operated to improve the data quality. If no sufficient amount of moving picture data has been stored on the recording medium when an error has occurred in the moving picture data read out from the recording medium, the retry means is operated to assure real-time performance. Thus, the moving picture data, required to be real-time data, can be reproduced as high-quality real-time data.
In still another aspect, the present invention provides a data reproducing apparatus for reproducing digital data from a recording medium including discriminating means for discriminating whether the digital data is compressed moving picture data or other data, data storage means for transiently storing the digital data read out from the recording medium, retry means for re-reading from the recording medium data corrupted with errors produced in the digital data read out from the recording medium and changeover means for switching the operation of the retry means, depending on the state of the data storage means at the time of error occurrence in the digital data read out from the recording medium if the digital data has been verified to be compressed moving picture data by the discriminating means.
In this data reproducing apparatus, the digital data read out from the recording medium is transiently stored in the data storage means. It is up to the discriminating means to verify whether the digital data is the compressed moving picture data or other data.
If, in the present data reproducing apparatus, the digital data has been verified by the discriminating means to be compressed moving picture data, and an error has occurred in the digital data read out from the recording medium, the switching means switches between performing and not performing the retry means of re-writing the error-corrupted data on the recording medium depending on the state of the data storage means prevailing as the error has been produced.
In the present data reproducing apparatus, the switching means switches between operating and not operating the retry means depending on the state of the data storage means when the error has occurred in the moving picture data read out from the recording medium, so that, in recording predetermined moving picture data required to be real-time data, the moving picture data can be reproduced as high-quality real-time data.
In still another aspect, the present invention provides a data reproducing method for reproducing compressed data from a recording medium, wherein switching is made between performing and not-performing the retry operation of re-reading from the recording medium the error-corrupted moving picture data at the time of error occurrence depending on the state at the time of error occurrence in the moving picture data read out from the recording medium of data storage means transiently storing moving picture data read out from the recording medium.
In this data reproducing apparatus, switching is made between performing and not performing the retry operation of re-reading the moving picture data corrupted with errors from the recording medium, when such error has been produced in the moving picture, depending on the state of the data storage means when the error has been produced. In more detail, if the data volume of data stored in the data storage means when an error is produced in the moving picture data read out from the recording medium exceeds the data volume of data transferred from the data storage means during the time the moving picture data of a data volume read out at a time from the recording medium is read out from the recording medium, the retry operation is performed to re-read the error-corrupted data from the recording medium, whereas, if the data volume of data stored in the data storage means when an error is produced in the moving picture data read out from the recording medium is less than the data volume of data transferred from the data storage means during the time the moving picture data of a data volume read out at a time from the recording medium is read out from the recording medium, the retry operation is not performed.
In the present data reproducing method, in which switching between performing and not performing the retry operation is made depending on the state of the data storage means prevailing when the error is produced in the moving picture data read out from the recording medium, such that, if a sufficient amount of picture data is stored in the data storage means when an error is produced in the moving picture data read out from the recording medium, the retry operation is performed to improve the data quality, whereas, if no sufficient amount of picture data is stored in the data storage means when an error is produced in the moving picture data read out from the recording medium, the retry operation is not performed to assure the real-time performance. Thus, it is possible to reproduce moving picture data, required to be real-time data, as high-quality real-time data.
In yet another aspect, the present invention provides a data reproducing method for reproducing digital data from a recording medium wherein the digital data is discriminated as to whether it is compressed moving picture data or other data, and wherein, if the digital data is verified to be compressed moving picture data, switching is made between performing and not performing the retry operation of re-reading from the recording medium error-corrupted moving picture data, if an error is produced in the moving picture data read out from the recording medium, depending on the state at the time of error occurrence in the moving picture data read out from the recording medium of data storage means transiently storing moving picture data read out from the recording medium.
With this data reproducing method, if the digital data to be reproduced is verified to be compressed moving picture data, the retry operation is or is not performed depending on the state of the data storage means prevailing when the error has been produced in the moving picture data read out from the recording medium, so that, if moving picture data, required to be real-time data, is to be reproduced, it can be reproduced as high-quality real-time data.
In a data recording apparatus according to the present invention, in which the retry operation of re-writing data corrupted with a writing error on the recording medium when such writing error is produced during the recording operation is or is not performed in a switching fashion depending on the state of the data storage means prevailing when the writing error has been produced, the moving picture data, required to be real-time data, can be optimally recorded as real-time data such as to suppress error occurrence during reproduction efficiently.
In another data recording apparatus according to the present invention, it is verified whether digital data to be recorded on a recording medium is compressed moving picture data required to be real time data, or other data, when the digital data is recorded on the recording medium. If this digital data is verified to be compressed moving picture data, the retry operation of rewriting data corrupted with the writing error is or is not performed, depending on the state of the data storage means prevailing when the writing error has occurred. Thus, the moving picture data, required to be real-time data, can be recorded as optimum real-time data, such as to exploit the data storage means efficiently and to suppress error occurrence on reproduction efficiently.
If, in the present data recording apparatus, the digital data to be recorded is data other than the compressed moving picture data, and the writing error is produced during recording, the retry operation can be repeatedly performed to write the data corrupted with the writing error a number of times until the writing error ceases to be produced, whereby the error occurrence on reproduction can be suppressed effectively to improve data reliability.
In a data recording method according to the present invention, the retry operation of re-writing data corrupted with a writing error when such writing error is produced during recording is or is not performed, depending on the state of the data storage means prevailing when the writing error has been produced. Thus, the moving picture data, required to be real-time data, can be recorded as optimum real-time data, such as to exploit the data storage means efficiently and to suppress error occurrence on reproduction efficiently.
In another data recording method according to the present invention, it is verified whether digital data recorded on a recording medium is compressed moving picture data required to be real time data, or other data, when the digital data is recorded on the recording medium. If the digital data is verified to be compressed moving picture data, the retry operation of re-writing data corrupted with a writing error is or is not performed, depending on the state of the data storage means prevailing when the writing error has occurred. Thus, the moving picture data, required to be real-time data, can be recorded as optimum real-time data, such as to exploit the data storage means efficiently and to suppress error occurrence on reproduction efficiently.
If, in the present data recording method, the digital data to be recorded is verified to be data other than the compressed moving picture data, and the writing error has been produced during recording, the retry operation can be repeatedly performed to write the data corrupted with the writing error a number of times until the writing error ceases to be produced, whereby the error occurrence on reproduction can be suppressed effectively to improve data reliability.
If, in a data reproducing apparatus according to the present invention, an error is produced in the data read out from the recording medium, the retry operation of re-reading error-corrupted data from the recording medium at the time of occurrence of an error in data read out from the recording medium is or is not performed depending on the state of the data storage means prevailing when the error is produced. Thus, the moving picture data, required to be real-time data, can be reproduced as real-time data such as to exploit the data storage means efficiently and to suppress error occurrence efficiently.
In another data reproducing apparatus according to the present invention, it is verified, in reproducing digital data from a recording medium, whether the digital data is compressed moving picture data required to be real-time data, or other data. If this digital data is verified to be compressed moving picture data, and an error is produced in the data read out from the recording medium, the retry operation of re-reading error-corrupted data from the recording medium is or is not performed, in a switching fashion, depending on the state of the data storage means prevailing when the error has occurred. Thus, the moving picture data, required to be real-time data, can be reproduced as real-time data such as to exploit the data storage means efficiently and to suppress error occurrence effectively.
Also, if, in the present data reproducing apparatus, the digital data to be recorded is verified to be data other than the compressed moving picture data, and an error is produced in the data read out from the recording medium, it is possible to perform the retry operation repeatedly to read out the error-corrupted data from the recording medium a number of times until the error ceases to be produced, thereby improving data reliability appreciably.
In a data reproducing method according to the present invention, if an error is produced in the data read out from the recording medium, the retry operation of re-reading the error-corrupted data from the recording medium is or is not performed, in a switching fashion, depending on the state of the data storage means prevailing when an error has been produced. Thus, the moving picture data, required to be real-time data, can be reproduced as real-time data, as the error occurrence is suppressed to improve reliability of the reproduced data.
If, in another data reproduced method according to the preset invention, digital data is to be reproduced from the recording medium, it is verified whether the digital data is compressed moving picture data required to be real-time data or other data. If the digital data is verified to be compressed moving picture data, and an error is produced in the data read out from the digital data, the retry operation of re-reading out the error-corrupted data from the recording medium is or is not performed, in a switching fashion, depending on the state of the datastorage means prevailing when the error has been produced. Thus, moving picture data, required to be real-time data, can be reproduced as real-time data, whereby reproduced data can be improved in reliability as error occurrence is suppressed efficiently.
If, in the data reproducing method, the digital data to be reproduced is verified to be data other than the compressed picture data, and an error is produced in the data read out from the recording medium, the retry operation can be repeatedly performed to read out error-corrupted data repeatedly until the error ceases to be produced, whereby error occurrence can be suppressed effectively to improve data reliability.